Rabiotraitsmitting system



T. R. BUNTING.

RADIOTRANSMITTING SYSTEM. APPLICATION FILED )UNEZ. 1920.

1,418,066. Patented May 30, 1922.

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anvemtc-z Cit tow e11 UNITED STATES THEODORE R. BUNTING,

PATENT OFFICE.

or NORFOLK, VIRGINIA.

RADIOTRANSMITTING SYSTEIVL To all whom it may concern:

Be it known that I, THEODORE R. BUN'r ING, a citizen of the United States, residing at 4.202 Granby Street, city of Norfolk, in the county of Norfolk and State of Virginia, have invented new and useful Improvements in Radiotransmitting Systems, of which the following is a specification.-

My invention relates to improvements in radio transmitting systems and the object in view is to provide electric circuits which will permit two messages to be transmitted simultaneously and independently by one antenna, by providing means for causing two oscillating currents of different frequencies to flow between the antenna and ground systems without interference with each other.

The invention contemplates the use of two parallel radiating circuits consisting of the same antenna and ground, between which are two electrical circuits each of which includes a tuning inductance and an impedance circuit composed of an inductance shunted by a capacity, each impedance circuit to be tuned to the frequency of the opposite radiating circuit, and the two radiating circuits to be tuned to oscillate at frequencies sufliciently different to render negligible the impedance of each impedance circuit to the oscillating current of the radiating circuit of which it is a part.

The invention contemplates further the use of the above-described parallel radiating circuits combined with means to compensate each impedance circuit for any change in the value of the electrical constants of its correspondingly opposite radiating circuit. This refers to the use of the duplex radiating system with undamped or continuous waves, the frequency of which is modified to accomplish signalling.

In the accompanying drawings, Fig. I

' shows diagrammatically a radiating antenna circuit for duplex radio transmission. Fig. II shows the same combined with two oscillating circuits having the same or different source of power, but generating diiferent high frequencies. Fig. III shows diagrammatically a duplex radio transmitting system using continuous waves, with means for altering the values of the constants of the two radiating circuits independently, and simultaneously compensating for such alterations.

Referring to the drawings: 1 designates an Specification of Letters Patent. Patented lap 30, 1922 1920. Serial No. 385,903.

antenna, 2 the earth connection, 3 and 3" mpedance circuits, and a and 4? tuning inductances, said impedance circuits and tuning inductances beinginsecrted in the branches of the antenna-earth circuit.

In Fig. II oscillating circuits are shown each comprising primary inductance 5 or 5, a condenser 6 or 6, a spark gap 7 or 7*; a transformer secondary winding 8 or 8, a transformer primary winding 9 or 9 an iron core 10 or 10 telegraph keys 1 1 or 14:", and a common source'of alternating electric energy 15, though the invention contemplates the use of either a common or different sources of said alternating electrical energy. The operation of the system above described is as follows: When the operator closes one of the keys, 14 for example, the energy from source 15 is transformed to the secondary winding 8, whence it is converted into high-frequency oscillating currents in the circuit 5, 6, 7, the electrical constants of which are of such value as to make these oscillations of the same frequency as the radiating circuit to which it is coupled by the primary inductance 5 and tuning inductance 4. The presence of the impedance circuit 3 prevents the oscillations of radiating circuit 1, 3, 4:, 2, from being inter fered with by the presence and electrical condition of the opposite radiating circuit 1, 3 1, 2. The invention, however, contemplates any method for generating damped oscillating currents whereby damped oscillating currents of different frequencies are independently caused to flow in the duplex radiating system described.

Referring to Fig. III, a generator of high frequency continuous or undamped oscillations 20 is connected in series with a capacity 21 between the antenna 1 and earth2. A source of electric energy 22 is connected through the telegraph keys 23, 24 to the electromagnetic contact closers 25, 26, 27 28, which control the value of the tuning inductances 4 and 4 and the use or non-use of the additional capacities 29, 30, which are included in the impedance circuits 3, 3. Any device, electrical or mechanical, may be used to control the value of either the inductance or the capacity of the impedance circuit simultaneously with the change in the tuning inductance of the opposite radiating circuit, such that the frequency of said impedance circuit shall be maintained coincident with the frequency of the wave radiated by the opposite radiating circuit.

The operation of the system described in Fig. 111 is as follows: Continuous oscillations of two different frequencies are normally flowing in the duplex radiating system described and signalling is accomplished by independently modifying the frequencies of the radiated waves. Upon closure of one of the keys, 23 for example, the devices 26 and 28 are simultaneously operated, changing the value of the tuning inductance of radiating circuit 1, 3, l, 2, and hence the frequency of the radiated wave, and also changing one of the constants of the impedance circuit 3, which in the case diagrammed is the capacity. The closure of the key 24: has the same effect upon the radiating circuit 1, 3*, P, 2, and impedance circuit 3. It is essential to the successful operation of this system that both the normal and the signalling waves shall be selected of such a frequency as to satisfy the condition that the impedance of each impedance circuit shall be negligible to the oscillating currents of the radiating circuit of which it is a part.

I claim:

In a radio transmitting system employing continuous or undamped waves the frequency of which is altered to accomplish signalling, the combination of two parallel radiating circuits consisting of the same antenna and the earth, between which are two electrical, circuits each of which includes a tuning inductance and an impedance circuit composed of an inductance shunted by a capacity, each impedance circuit tuned to the frequency of the opposite radiating circuit and the two radiating circuits tuned to oscillate at frequencies sufficiently different to render negligible the impedance of each impedance circuit to the oscillating current of the radiating circuit of which it is a part, means for independently changing the value of the electrical constants of the two radiating circuits to accomplish the transmission of two messages, and simultaneously with each operation to automatically compensate, for such change, the value of the electrical constants of the impedance circuit included in the opposite radiating circuit.

In testimony whereof I affix my signature.

THEODORE R. BUNTING. 

